| [OBJECTIVE]The repair of Achilles tendon defect is always one of the difficult and hot points in clinical diagnosis and treatment.Tissue engineering Achilles tendon has become a new potential way to replace the traditional transplantation and repair methods.Based on the fabrication of controllable fiber and porous scaffolds by electrohydrodynamic 3D printing,the purpose of this study was to improve the poor biocompatibility and slow degradation of poly-(ethylene terephthalate)(PCL)by mixing the hydrophilic copolymer Pluronic-F127,a scaffold with controllable pore size and fiber arrangement was constructed and combined with cells to repair Achilles tendon defect in rats.it will provide the experimental basis for the future clinical application of tissue engineering Achilles tendon.[METHODS]The printing ink was prepared by blending 1%,3%and 5%Pluronic-F127 with PCL by mass-volume ratio.The stent was fabricated by electrohydrodynamic 3D printing.The mechanical properties were tested by a tensile-pressure tester,the young’s Modulus was calculated,the wettability was evaluated according to the water contact angle,and the properties were characterized by scanning electron microscope before and after enzymatic degradation in vitro,the surface morphology of the scaffolds was evaluated,and the degradation rate of the scaffolds was calculated according to the ratio of weight loss.Then,C3H10T1/2 cell was implanted into the scaffold,and the cell viability was evaluated by Ca-AM/PI staining and the cell proliferation rate was evaluated by Edu staining on Day 1,3 and 7.Respectively,F-actin staining was used to evaluate the migration ability of cells on different scaffolds.A immunosuppressed rat model with Achilles tendon defect was established.The scaffold was transplanted to the Achilles tendon defect.The rats were sacrificed 2 and 4 weeks after operation,the effect of Tissue Engineering scaffold in the treatment of Achilles tendon defect was evaluated by the strength and HE staining of Achilles Tendon.[RESULTS]The scaffold with controllable fiber and porosity made by Pluronic-F127 and PCL as printing ink could be accomplished by electrohydrodynamic 3D printing,and the degradation rate of the material was accelerated.The spongy pore structure was observed under the electron microscope,which was beneficial to cell adhesion,however,5%F127/PCL can obtain the most excellent wettability,the fastest degradation rate,and the controllable fiber and pore size scaffolds which meet the basic mechanical requirements.In cell experiments,the Ca-AM/PI staining of PCL and 5%F127/PCL scaffolds showed a good biocompatibility,indicating that the material was biologically safe.The Edu staining show that the addition of F127 increased the number of cells adhering to the scaffolds,the results showed that F127 significantly improved the cell adhesion of the stents.F-actin results showed that 5%F127/PCL scaffold had better cell migration ability.In vivo,tendon with PCL or 5%F127/PCL scaffolds were superior to one without the scaffolds in mechanical strength,but there was no significant difference between the PCL and 5%F127/PCL groups in mechanical strength.HE results show tissue engineering scaffolds make the arrangement of early collagen fibers more orderly and are more beneficial to the deposition of extracellular matrix.The addition of exogenous fibroblasts can provide more favorable conditions for the repair of Achilles tendon.The addition of F127 made the material more conducive to cell adhesion,and showed obvious advantages in cell density at 2 weeks.[CONCLUSIONS]Electrohydrodynamic 3D printing can construct tissue engineering scaffolds with controllable fibers and good porosity.F127 can improve the hydrophilicity and degradation of PCL in vitro.Although the mechanical properties of PCL decrease,more excellent micro-scale structure and nano-pore scaffolds are obtained.The PCL scaffolds with 5%F127 seeded were favorable for C3H10T1/2 cell adhesion and growth,and had good pore structure,which indicated that the scaffolds had good Biocompatibility.Cells and scaffolds were transplanted into rats with Achilles tendon defect.The tissue engineering scaffolds made the arrangement of Collagen fibers more orderly.The scaffolds with 5%F127 were beneficial to the accumulation and arrangement of collagen fibers. |
